Thread cutting mechanism

ABSTRACT

A thread-cutting mechanism for a sewing machine having a finger member movable after the first cyclical stroke of the needle for removing and retaining the beginning end of the thread located underneath the garment from the reciprocal path of movement of said needle. After the last cyclical stroke of the needle, the finger member returns to its rest position and in so doing severs the thread retained by a looper member underneath the garment, whereby both the beginning and trailing ends of the thread are concealed from view.

United States Patent 72] Inventor Gilbert A. Littell.

Versailles, Ky.

[21 Appl. No. 828,173

[22] Filed May 27, 1969 [45] Patented Feb. 2, 1971 [73] Assignee Textron Inc.

a corporation of Delaware [54] THREAD CUTTING MECHANISM 9 Claims, 8 Drawing Figs.

[52] US. Cl 112/252 [51] Int. Cl. D05b 65/00 [50] Field of Search 112/252, 130,129,105, 110,111,112

[56] References Cited UNITED STATES PATENTS 1,404,727 l/1922 Allen 112/252 1,962,903 6/1934 Lyons 112/252 2,474,710 6/1949 Wood.... 112/252 2,826,160 3/1958 Adams 112/252 3,470,835 10/ 1969 Saganowich et al. 1 12/252 Primary Examiner-H. Hampton Hunter Attorney-Meech & Field ABSTRACT: A thread-cutting mechanism for a sewing machine having a finger member movable after the first cyclical stroke of the needle for removing and retaining the beginning end of the thread located underneath the garment from the reciprocal path of movement of said needle. After the last cyclical stroke of the needle, the finger member returns to its rest position and in so doing severs the thread retained by a looper member underneath the garment, whereby both the beginning and trailing ends of the thread are concealed from view.

PATENTJEU FEB 2m?! SHEET 1 0F 2 INVENTOR. @IZBERT A L/rreu BY fiead f M TORNEYS.

THREAD CUTTING MECHANISM BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a mechanism for a sewing machine and more particularly to an improved mechanism for a sewing machine that severs the ends of the thread securing two articles together and then places the severed ends of the thread under the articles and out of sight.

2. Description of the Prior Art In the prior art, there has been employed thread-severing means for trimming the beginning needle-thread, prior to the first sewing cycle, and for severing the last needle-thread loop at the close of the sewing operation. Generally, this thread severing means includes a plurality of separately movable devices, one of which is for first gathering the beginning thread end and retaining the same in a given position removed from the area of the reciprocating needle during the sewing cycle. At the end of the sewing cycle, the sewing thread passing about the looper is formed into two strands of thread spaced close to each other. A- knife member, mounted separately from the means for gathering the beginning thread end and retaining the same, is actuated to sever one of the thread strands about the looper. Because of the close proximity of the two strands, the knife member generally comprises a plurality of interconnected and interacting movable members for performing the thread-severing operation.

SUMMARY OF THE INVENTION According to the present invention, an improved sewing machine mechanism is provided which comprises a single movable blade member having an opening therein for gathering the beginning free end of the thread. On the first cycle of the sewing machine, the sewing thread partially encircles the looper member and passes through the eye of the needle to the supply. The free end of the thread is caught by the blade and moved therewith to a second position where it is nipped between a pressure pad and the blade, with the free end of the thread located on the bottom side of the garment. Once the sewing cycle is completed, and the needle has cleared the garment, the blade returns to its original position and, in doing so, separates the two strands of the thread looped about the looper member, whereby only that strand located intermediate the eye of the needle and the looper is severed upon a stationary knife.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation view of the head of a sewing machine in which the present invention can be conveniently embodied;

FIGS. 2 through 5 are enlarged perspective views of the sewing machine mechanism of this invention with parts of the sewing machine of FIG. 1 cut away to show the sequence of operation of the mechanism during the first cycle of the machine; and,

FIGS. 6 through 8 are enlarged perspective views of the sewing machine mechanism of this invention, similar to FIGS. 2 through 5, showing the operation of the mechanism during the last cycle of the machine.

DESCRIPTION OF A PREFERRED EMBODIMENT The sewing machine shown in FIG. 1 includes an overhanging bracket arm 10 and head 12 carrying the reciprocating eye pointed needle 14 which cooperates with a rotary chain stitch looper member 16. Needle l4 and looper member 16 are geared to the main shaft of an electric motor (not shown) so that each is driven in synchronism relative to the other when the motor rotates. In operation, needle 14 is thrust through an article such as an eyelet carrying member, through the cloth the member is to be secured to, and thence through an opening in the throat plate 18. Needle l4 continues to the bottom of its stroke and then starts to return, when it throws out a loop of thread which rotating looper member 16 siezes. As needle 14 continues to move upwardly, the thread 20 is withdrawn from the eye 22 of needle 14, while simultaneously looper member 16 rotates to form a chainstitch. The operation of the machine is controlled by the operator and normally includes provision for stopping the machine with needle 14 at the top of its stroke.

In FIGS. 2 through 5, there is shown an embodiment of the improved mechanism in accordance with the invention. An eye member 24 having two pairs of eyelets, 26, 26 and 28, 28, respectively, is positioned on throat plate 18 of the machine with one eyelet 26 positioned in registry with the opening (not shown) in the throat plate. Reciprocating needle 14 carrying a thread 20 through its eye 22, will move downwardly along a path which will carry it through eye 26 of eye member 24, through the opening in throat plate 18 into the proximate vicinity of the nose 30 of looper member 16. Adjacent the opening in throat plate 18 and to one side of looper member 16 is a spring loaded adjustable pressure pad 32 which is carried by a support 34 and which is shown as being cooperable with the bottom surface of throat plate 18. The free end portion of a pivotally mounted flat-bladed finger 36 is shown in FIG. 2 in its rest position wherein it is located underneath a stationary knife blade 38 secured to the lower surface of throat plate 18. Finger 36 has an arcuate shape with a substantially circular cutout 40 located along its edge 42 facing looper member 16 and needle 14. Divergent guideway edges 44 connect cutout 40 with edge 42 of finger 36. A curved cam edge 46 is located beyond cutout 40 and towards the tip of finger 36. At substantially the remote end of finger 36, there is located a slightly concavely curved edge 50 which cooperates with the lower biased edge 52 of stationary knife 38. In its movement, finger 36 moves about a pivot point, not shown, such that curved edge 46 when moved in the vicinity of the path of needle 14, will tend to engage and act as a cam surface to urge a transverse member out of its path of movement as will be explained more fully herein below. The description of the mechanism given above has been with particular reference to FIG. 2, wherein the drawing corresponds substantially to the rest position of the mechanism.

In operation, as shown in FIGS. 2-5, the operator actuates the controls of the sewing machine to start the sewing cycle and needle 14 starts downwardly through eyelet 26. Thread 20 passes through eye 22 of needle 14 and has a free end 54 thereof which is carried along with the needle as it passes successively through eyelet 26, cloth (not shown) and the opening in throat plate 18. In FIG. 3, needle 14 has passed through bottom dead center in its reciprocal movement and a loop 56 is formed in thread 20 of free end 54. At this moment, nose 30 of looper member 16, now rotating continuously in the direction F about its axis, inserts itself into loop 56 to retain the free end 54 of thread 20 beneath throat plate 18. As needle l4 retracts, finger blade 36 pivots in a clockwise direction, as shown in FIG. 4, to pick up and carry with it the two strands of thread looped about looper member 16. The strands of thread are guided by guideway edges 44 into cutout 40; and, as finger blade 36 pivots further, the free end strand 54 is unwound from looper member 16 so that only one strand is carried in cutout 40 of finger blade 36 into sliding engagement with pressure pad 32 where it is pinched and held in place. Needle l4 continues to rise, as shown in FIG. 5, out of eyelet 26 of eye member 24, whereat needle 14 is prepared to enter the second cycle which will enter the second eyelet 26 of eye member 24. It should be noted that the free end 54 of thread 20 is now located beneath eye member 24, and, as a matter of fact, is beneath the cloth carrying eye member 24. Each reciprocal motion of needle 14 produces another stitch alternately through the eyelets 26, 26' for securing the article to the cloth with the number of stitches predetermined by preset controls.

As shown in FIGS. 6-7, at the end of the sewing cycle, needle 14 moves upwardly to its rest position. Needle 14 is shown as moving upwardly through eyelet 26' with one strand 60 of thread passing through eyelet 26', through the cloth (not shown), and through throat plate 18. Strand 60 is looped about looper member 16 and is connected to strand 62 which passes through the opening in throat plate 18, through the cloth (not shown), through eyelet 26' and is passed about the bridging portion of eye member 24 and through eyelet 26. In FIG. 6 finger 36 has started to move in the direction C about its pivot point and has released the free end 54 from engagement with pad 32. Free end 54 will remain stationary as there is no tension force exerted on it.

In FIG. 7, finger 36 has continued in its movement such that edge 50 at the tip of the finger has engaged strand 62, and because edge 50 is concavely curved, will retain strand 62 therewith and carry it along. Curved cam edge 46 transversely engages strand 60 and biases the same out of the path of movement of edge 46 and, in effect, cams strand 60 away. The movement of finger 36 creates a tension on thread 20 which tends to pull more thread from the supply so that finger 36 does not have to overcome a substantially great and immovable force.

As finger 36 continues to move, as best shown in FIG. 8, strand 62 captured by concavely curved edge 50 is carried therewith and into engagement with cutting edge 52 of knife 38 to sever the thread. Once the thread is severed, the cloth carrying eye member 24 is moved from the position shown in FIG. 8 so that eyelet 28 is brought into registry with the opening in throat plate 18. In so moving, the severed ends of the thread securing eye member 24 to the cloth are withdrawn from the opening in throat plate 18 and the newly severed end 54, as shown in FIG. 8 is withdrawn from eyelet 26' of eye member 24 and will be positioned above eye member 24 substantially as shown in FIG. 2. Thus, the sewing machine is now ready for the operator to actuate the controls to again start the sewing cycle. It is to be understood that needle 14 will start downwardly through eyelet 28 and the attaching thread 20 will alternately pass through eyelet 28 and 28, meanwhile passing over the bridging portion located intermediate these eyelets to secure the eyelet member to the cloth.

It will be obvious that the severed ends of the attaching thread will be located underneath the cloth to which the eye member is secured and thus in a position where the same ends are out of view.

The invention has been described in detail with particular reference to an embodiment thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

lclaim:

1. In a sewing machine for forming a group of stitches at substantially the same point in a piece of material including the stitch forming mechanism; of a reciprocating needle, adapted to move in and out of an opening in the throat plate of said sewing machine, and of a looper member located beneath said opening in said throat plate, the improved combination comprising:

a pressure pad and first means movable from a rest position on one side of said opening to a second position on the other side of said opening, for clasping, after the first cyclical stroke of said needle, the beginning end of the thread pulled down by said looper member and pinching said beginning end between said first means and said pressure pad when in said second position;

means for shifting said first means from said second position to the rest position on the last cyclical stroke of said needle to release said beginning end of said thread wherein the continuous thread is looped about said looper to form two spaced-apart strands of thread thereof, one strand extending from the work piece and passing through said opening in said throat plate and about said looper member, and a second strand extending from said looper member through said opening in said throat plate and through the eye of said needle; a stationary cutting member, and second means on said first means, as it moves from said second position to said rest position, for transversely engaging said one strand of said thread and driving the same onto said cutting member; and

whereby said beginning end and the trailing end of said thread is located on the same side.

2. The improved sewing machine according to claim 1, wherein said first means includes a flat blade member mounted to pivot about one end to move the free end from said rest position to said second position.

3. The improved sewing machine according to claim 2, wherein said fiat blade member includes a cutout adjacent its free end for nipping said beginning end of said thread and moving the same into engagement with said pressure pad.

4. The improved sewing machine according to claim 3, wherein said flat blade member slidably engages and moves across said pressure pad with the beginning end of said thread nipped between the surface of said flat blade and the surface of said pressure pad.

5. The improved sewing machine according to claim 3, wherein said cutout adjacent said free end of said blade includes a wedge shaped portion for gathering said thread and a circular cutout portion at the apex of said wedge shaped portion for clasping the thread therein and transporting the same as said fiat blade member moves from said rest position to said second position.

6. The improved sewing machine according to claim 2, wherein said second means is located on said flat blade member at said free end.

7. The improved sewing machine according to claim 6, wherein said second means is a concavely curved edge surface for transversely engaging said thread strand when said flat blade member moves from said second position to said rest position.

8. The improved sewing machine according to claim 7, wherein said sharpened edge drives said thread unto a stationary knife member which cooperates with said sharpened edge.

9. The improved sewing machine according to claim 7, wherein a curved cam surface is located on said edge of said flat blade member intermediate said concavely curved edge surface and said cutout for slidably engaging said second strand and urge the same out of the path of said concavely curved edge. 

1. In a sewing machine for forming a group of stitches at substantially the same point in a piece of material including the stitch forming mechanism; of a reciprocating needle, adapted to move in and out of an opening in the throat plate of said sewing machine, and of a looper member located beneath said opening in said throat plate, the improved combination comprising: a pressure pad and first means movable from a rest position on one side of said opening to a second position on the other side of said opening, for clasping, after the first cyclical stroke of said needle, the beginning end of the thread pulled down by said looper member and pinching said beginning end between said first means and said pressure pad when in said second position; means for shifting said first means from said second position to the rest position on the last cyclical stroke of said needle to release said beginning end of said thread wherein the continuous thread is looped about said looper to form two spaced-apart strands of thread thereof, one strand extending from the work piece and passing through said opening in said throat plate and about said looper member, and a second strand extending from said looper member through said opening in said throat plate and through the eye of said needle; a stationary cutting member, and second means on said first means, as it moves from said second position to said rest position, for transversely engaging said one strand of said thread and driving the same onto said cutting member; and whereby said beginning end and the trailing end of said thread is located on the same side.
 2. The improved sewing machine according to claim 1, wherein said first means includes a flat blade member mounted to pivot about one end to move the free end from said rest position to said second position.
 3. The improved sewing machine according to claim 2, wherein said flat blade member includes a cutout adjacent its free end for nipping said beginning end of said thread and moving the same into engagement with said pressure pad.
 4. The improved sewing machine according to claim 3, wherein said flat blade member slidably engages and moves across said pressure pad with the beginning end of said thread nipped between the surface of said flat blade and the surface of said pressure pad.
 5. The improved sewing machine according to claim 3, wherein said cutout adjacent said free end of said blade includes a wedge shaped portion for gathering said thread and a circular cutout portion at the apex of said wedge shaped portion for clasping the thread therein and transporting the same as said flat blade member moves from said rest position to said second position.
 6. The improved sewing machine according to claim 2, wherein said second means is located on said flat blade member at said free end.
 7. The improved sewing machine according to claim 6, wherein said second means is a concavely curved edge surface for transversely engaging said thread strand when said flat blade member moves from said second position to said rest position.
 8. The improved sewing machine according to claim 7, wherein said sharpened edge drives said thread unto a stationary knife member which cooperates with said sharpened edge.
 9. The improved sewing machine according to claim 7, wherein a curved cam surface is located on said edge of said flat blade member intermediate said concavely curved edge surface and said cutout for slidably engaging said second strand and urge the same out of the path of said concavely curved edge. 